public class MyUtil {
    public static String percentage2fivegrade(int grade) {
        if (grade<0)
            return "错误";
        else if(grade < 60)
            return "不及格";
        else if (grade<70)
            return "及格";
        else if (grade<80)
            return "中等";
        else if (grade<90)
            return "良好";
        else if (grade<101)
            return "优秀";
        else
            return "错误";
    }
}